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/*
* Copyright 2008-2013 NVIDIA Corporation
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#pragma once
#include <thrust/detail/config.h>
#include <thrust/iterator/transform_iterator.h>
#include <thrust/iterator/zip_iterator.h>
#include <thrust/iterator/counting_iterator.h>
#include <thrust/tuple.h>
#include <thrust/functional.h>
THRUST_NAMESPACE_BEGIN
namespace detail
{
template<typename RandomAccessIterator,
typename BinaryPredicate = thrust::equal_to<typename thrust::iterator_value<RandomAccessIterator>::type>,
typename ValueType = bool,
typename IndexType = typename thrust::iterator_difference<RandomAccessIterator>::type>
class tail_flags
{
// XXX WAR cudafe bug
//private:
public:
struct tail_flag_functor
{
BinaryPredicate binary_pred; // this must be the first member for performance reasons
RandomAccessIterator iter;
IndexType n;
typedef ValueType result_type;
__host__ __device__
tail_flag_functor(RandomAccessIterator first, RandomAccessIterator last)
: binary_pred(), iter(first), n(last - first)
{}
__host__ __device__
tail_flag_functor(RandomAccessIterator first, RandomAccessIterator last, BinaryPredicate binary_pred)
: binary_pred(binary_pred), iter(first), n(last - first)
{}
__host__ __device__ __thrust_forceinline__
result_type operator()(const IndexType &i)
{
return (i == (n - 1) || !binary_pred(iter[i], iter[i+1]));
}
};
typedef thrust::counting_iterator<IndexType> counting_iterator;
public:
typedef thrust::transform_iterator<
tail_flag_functor,
counting_iterator
> iterator;
__thrust_exec_check_disable__
__host__ __device__
tail_flags(RandomAccessIterator first, RandomAccessIterator last)
: m_begin(thrust::make_transform_iterator(thrust::counting_iterator<IndexType>(0),
tail_flag_functor(first, last))),
m_end(m_begin + (last - first))
{}
__thrust_exec_check_disable__
__host__ __device__
tail_flags(RandomAccessIterator first, RandomAccessIterator last, BinaryPredicate binary_pred)
: m_begin(thrust::make_transform_iterator(thrust::counting_iterator<IndexType>(0),
tail_flag_functor(first, last, binary_pred))),
m_end(m_begin + (last - first))
{}
__host__ __device__
iterator begin() const
{
return m_begin;
}
__host__ __device__
iterator end() const
{
return m_end;
}
template<typename OtherIndex>
__host__ __device__
typename iterator::reference operator[](OtherIndex i)
{
return *(begin() + i);
}
private:
iterator m_begin, m_end;
};
template<typename RandomAccessIterator, typename BinaryPredicate>
__host__ __device__
tail_flags<RandomAccessIterator, BinaryPredicate>
make_tail_flags(RandomAccessIterator first, RandomAccessIterator last, BinaryPredicate binary_pred)
{
return tail_flags<RandomAccessIterator, BinaryPredicate>(first, last, binary_pred);
}
template<typename RandomAccessIterator>
__host__ __device__
tail_flags<RandomAccessIterator>
make_tail_flags(RandomAccessIterator first, RandomAccessIterator last)
{
return tail_flags<RandomAccessIterator>(first, last);
}
} // end detail
THRUST_NAMESPACE_END
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